Electron tube



G. DOBKE Oct. 24, 1939.

ELECTRON TUBE Filed March 15, 1954 INVENTOR GU ENTHER O BKE we ATTORNEY Patented Oct. 24, 1939 UNITED STATES ELECTRON TUBE Guenther Dobke, Berlin-Reinickendorf, Germany,

assignor to Allgemeine Elektricitats Gesellschaft, Berlin, Germany, a corporation of Germany Application March 15, 1934, Serial No. 715,587 In Germany March 23, 1933 1 Claim.

The present invention relates in general to electronic devices of the cathode ray or Braun tube type. More particularly the novel features of the present invention reside in providing a cathode ray or Braun type tube, such as an oscillograph or television image reproducing tube,

' where the electron acceleration system, together with the deviation system, is directed to the border zone of the fluorescent screen structure at one end of the tube.

As shown in the figure, the tube consists of a glass vessel I of known shape. The vessel or tube envelope I may be evacuated or may be filled with gas or vapor, preferably rare gas such as argon of low pressure, in order to produce concentrated rays; Furthermore, the envelope l is provided at the end thereof remote from the electron source with a fluorescent screen 2 of any known or suitable type.

In accordance with the novel feature of this invention the acceleration system producing the electron ray, as well as the deviation system influenced by the performance to be recorded, are

so oriented within the tube, that the axis A of the steady electron ray, 1. e. of the ray not deviated, forms an angle with the tube axis A, preferably in such a way that the ray axis is directed to the border zone of the fluorescent screen 2. The acceleration system suitably consists of a directly or indirectly heated cathode 3, a preliminary anode 4, formed for'instance of a disk with central opening, a Wehnelt cylinder or concentration cylinder 5, and a primary anode B, which likewise may consist of a disk having a 35 central opening 6. The preliminary anode 4' and the primary anode 6 may have equal potentials applied thereto and thus, where desired,

may be electrically connected. The cathode 3,

the anodes 4 and 6 and the Wehnelt cylinder 5 b are supported within the tube envelope l by mounting and lead-in wires, suitably sealed airtight in the common press lot the tube and extended outside the tube.

The deviation or deflecting system for bending the cathode, ray beam or pencil developed consists of two pairs of plates 8 and 9 of known construction and disposed at right angles to each other. If the application of the tube is, for the purpose of illustration, assumed to be for oscilloscope work, one pair of plates may serve for the time deviation or deflection of the developed cathode ray, for instance, by means of a relaxation circuit or any desired and suitable type (not shown), and the other pair of plates causes 55 the deviation or deflection of the developed cathode ray under the control of the electrical value to be recorded or viewed upon the screen 2.

It will be noted that according to the novel features of this invention the acceleration system and the deflection or deviation system are oriented in such manner that the axis of the electron or cathode ray A is directed to the border zone of the fluorescent screen.

The advantage of the novel orientation of the electron ray over the hitherto customary orientation of the ray to the center of the fluorescent screen resides in the fact that for the time deviation of the ray no special biasing potential is required so as to transmit the initial point of the recording to the border zone of the fluorescent screen in order to thereby permit utilization of the entire surface of the screen for recording, which as a rule extends throughout several periods of the performance to be recorded. At the same time by this orientation of the ray the so-c a lled anomaly of the zero point which appears o a greater or lesser extent at the height of the steady electron ray and resulting into a non-linearity of the deviation of the ray is substantially avoided and no longer has a disturbing influence upon the reproduction of light values.

In the operation of cathode ray tubes with the usual and customary arrangement of the electrodes, and particularly with tubes having a gaseous filling within the enclosing envelope, it has been found that bright spots will be caused at the center of the screen due to the ionization caused by the presence of the gas. This present invention has, therefore, the important advantage of removing any such resulting light spot to the edge of the screen where it is not noticeable.

Having now described the invention, what is claimed is:

An electron tube comprising an enclosing envelope symmetrical throughout its length and formed as an annular solid of revolution about the longitudinal axis of the tube, a luminescent target positioned adjacent the inner surface of one end of the tube and curved substantially symmetrically to the longitudinal axis of the tube, a tube neck having a stem and a press member coinciding in position with the longitudinal axis of the tube, an electron gun structure for developing a beam of electrons mounted within the tube neck and supported from the stem member and located at the opposite end of the tube from said target, said gun being supported in angular position relative to the longitudinal tube axis for directing the normal undeflected electron beam developed thereby upon the edge portion of the target only, and an electron beam deflecting system supported in axial alignment with the gun structure and also positioned at an angle with respect to the longitudinal tube ax1s.

GUENTHER DOBKE. 

